1. Technical Field
This invention relates generally to sailing yachts, and more particularly to a high performance canting ballast twin foil (CBTF) sailing yacht having a laterally movable ballast suspended beneath the hull that provides a counter heeling force when the yacht is underway.
2. Description of Related Art
U.S. Pat. Nos. 5,163,377 and 5,622,130 describe various aspects of a keel-less sailing yacht that has fore and aft cambered foils for leeway control and a dynamic gravitational ballast for heeling resistance. Twin foils mounted to depend from the hull are controlled by a hydraulic or electric system. A ballast-supporting structure in the form of an elongated strut extending downwardly from the hull supports the ballast generally beneath the hull. The proximal or near end of the strut is mounted on the hull pivotally and the distal or far end is connected to the ballast. Suitable means are provided (e.g., hydraulic drive components) for swinging the strut between port and starboard limits of travel. That arrangement enables a crew member to move the ballast to desired positions intermediate the port and starboard limits of travel while underway for a desired counter-heeling effect.
A keel-less sailing yacht with movable ballast is sometimes referred to as a canting ballast twin foil (CBTF) sailing yacht. Such CBTF sailing yachts enjoy recognized sailing success accompanied by significant interest in CBTF technology. However, various structural and operational concerns need attention. Larger sailing yachts, for example, including those designed for ocean racing or cruising, require greater force to move the ballast-supporting structure. Although hydraulic means have been suggested for prior art canting ballast systems, larger sailing yachts impose structural and operational limitations on a hydraulic cylinder and related hydraulic drive components used to move the ballast-supporting structure. The probability of catastrophic hydraulic component failure increases, and so a need exists for a better way to move the ballast on larger sailing yachts.
U.S. patent application Ser. No. 10/646,326 filed Aug. 22, 2003 (the parent application of which this application is a continuation in part, which parent application is now abandoned) addresses the above-described need by providing an onboard ballast drive system for moving the ballast under operator control. The system includes dual hydraulic cylinders connected to different portions of the hulls. Multiple hydraulic pumps may be included along with crossover hydraulic pressure lines to allow any pump to serve any one or two or more hydraulic cylinders. A redundant system with better force distribution results that significantly reduces the risk of failure of any part of the system when engaged in ocean racing or cruising. Although the onboard ballast drive system is effective, it is desirable to expand upon the means of powering it.